In this lesson, we’ll discuss the parts of the yellow fever virus’ structure and what functions those parts perform during infection and replication.
We’ll also learn about symptoms and treatment of the disease that the yellow fever virus causes.
What Is the Yellow Fever Virus?
Imagine coming down with the flu. You get a fever and your body starts to ache. You might feel nauseous or have spells of vomiting. Your head hurts and you shiver and curl up under a blanket, even though your face is covered in cold sweat.
Normally, you consume soup or tea or both, perhaps some pain reliever, and recover in a few days. Your immune system fights off the flu virus and you’re back to your old healthy self.However, this isn’t always how the situation plays out. Some viruses are far more deadly than those that cause the flu. The yellow fever virus causes acute hemorrhagic disease in which your fever worsens and your internal organs start to bleed, despite the initial symptoms resembling those of the flu.
Yellow fever virus is transmitted through mosquito bites and is mostly prevalent in Africa, although some cases have been recorded in tropical South America. Today, we’ll examine the parts of the yellow fever virus’ structure and their functions in causing these life-threatening symptoms.
Yellow Fever Virus Structure
Although they are so small they cannot be seen through the lenses of an optical microscope, viruses can be quite deadly. All viruses have a similar structure; all viruses have a genome and a nucleocapsid, and some have an envelope, too.The nucleocapsid is a protein coat that protects the genome of the virus.
A genome is the genetic material of the virus. Some virus’ genomes are composed of DNA, while others are made of RNA. Yellow fever virus is a single-stranded RNA virus, meaning only one strand of RNA comprises its genome. Like those of some other viruses, yellow fever virus’ envelope is a flexible coat made of lipids, or fats, that cover the nucleocapsid.
Symptoms and Treatments
The symptoms of yellow fever start out looking like the flu, as described earlier in the lesson. Most patients recover from this phase, but some enter a second phase with more serious consequences.
In the second phase, which occurs about a day after the initial symptoms disappear, liver cells die and the resulting liver failure results in jaundice. Jaundice is a yellowish color in the skin and eyes due to a change in the skin’s normal color.
Yellow fever is a virus that causes hemorrhagic disease, or one that results in bleeding. Soon after the appearance of jaundice, internal bleeding occurs and kidney function deteriorates, causing patients to begin bleeding through the nose and mouth. About 50% of patients recover from this stage, while the other 50% die within 10 to 14 days. Unfortunately, no treatment exists for yellow fever.
People traveling to Africa or South America are strongly advised to get the yellow fever vaccine, which can prevent infection by the yellow fever virus.
In summary, yellow fever virus causes acute hemorrhagic disease in which your fever worsens and your internal organs start to bleed, despite the initial symptoms resembling those of the flu. It’s a flavivirus – which is a small, enveloped virus whose diameter ranges in size from 40 to 60 nm – with a positive-sense single-stranded RNA genome, which means the RNA is in the correct order for the host cell to copy directly to produce protein.A nucleocapsid made of C proteins surrounds the RNA genome, and a lipid envelope studded with E and M proteins, which help the E proteins, covers the nucleocapsid.
E proteins are used for attachment to host cells. The viruses then enter the host cells by becoming encapsulated in an endosome, or membrane-bound vesicle. Next, the viruses release most of their RNA genomes into the cell. The cell unknowingly copies the virus’ RNA, making more viral particles.
The host cell fills with so many viruses that it dies, and the new viruses are released. Because the new viral particles are cloaked in the host cell’s endoplasmic reticulum (ER) membrane, which is a structure made of membranes that produce proteins, they’re camouflaged from the host’s immune system.The virus infects liver cells, resulting in jaundice, and eventually causes internal bleeding and kidney failure. Although there is no treatment, travelers can be given a yellow fever vaccine to prevent infection.Medical Disclaimer: The information on this site is for your information only and is not a substitute for professional medical advice.